Function (SQLite JDBC 3.30.1 API)

java.lang.Object
- org.sqlite.Function

Direct Known Subclasses:

Function.Aggregate
```
public abstract class Function
extends Object
```
Provides an interface for creating SQLite user-defined functions.
A subclass of org.sqlite.Function can be registered with Function.create() and called by the name it was given. All functions must implement xFunc(), which is called when SQLite runs the custom function.
Eg.
```
      Class.forName("org.sqlite.JDBC");
      Connection conn = DriverManager.getConnection("jdbc:sqlite:");

      Function.create(conn, "myFunc", new Function() {
          protected void xFunc() {
              System.out.println("myFunc called!");
          }
      });

      conn.createStatement().execute("select myFunc();");
  
```
Arguments passed to a custom function can be accessed using the protected functions provided. args() returns the number of arguments passed, while value_<type>(int) returns the value of the specific argument. Similarly a function can return a value using the result(<type>) function.

Aggregate functions are not yet supported, but coming soon.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`Function.Aggregate` Provides an interface for creating SQLite user-defined aggregate functions.
`static class`	`Function.Window` Provides an interface for creating SQLite user-defined window functions.

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`FLAG_DETERMINISTIC` Flag to provide to `create(Connection, String, Function, int)` that marks this Function as deterministic, making is usable in Indexes on Expressions.

Constructor Summary

Constructors
Constructor and Description

Function()

Constructors
Constructor and Description
`Function()`

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`protected int`	`args()` Returns the number of arguments passed to the function.
`static void`	`create(Connection conn, String name, Function f)` Registers a given function with the connection.
`static void`	`create(Connection conn, String name, Function f, int flags)` Registers a given function with the connection.
`static void`	`create(Connection conn, String name, Function f, int nArgs, int flags)` Registers a given function with the connection.
`static void`	`destroy(Connection conn, String name)` Removes a named function from the given connection.
`static void`	`destroy(Connection conn, String name, int nArgs)` Removes a named function from the given connection.
`protected void`	`error(String err)` Called by `xFunc` to throw an error.
`protected void`	`result()` Called by `xFunc` to return a value.
`protected void`	`result(byte[] value)` Called by `xFunc` to return a value.
`protected void`	`result(double value)` Called by `xFunc` to return a value.
`protected void`	`result(int value)` Called by `xFunc` to return a value.
`protected void`	`result(long value)` Called by `xFunc` to return a value.
`protected void`	`result(String value)` Called by `xFunc` to return a value.
`protected byte[]`	`value_blob(int arg)` Called by `xFunc` to access the value of an argument.
`protected double`	`value_double(int arg)` Called by `xFunc` to access the value of an argument.
`protected int`	`value_int(int arg)` Called by `xFunc` to access the value of an argument.
`protected long`	`value_long(int arg)` Called by `xFunc` to access the value of an argument.
`protected String`	`value_text(int arg)` Called by `xFunc` to access the value of an argument.
`protected int`	`value_type(int arg)` Called by `xFunc` to access the value of an argument.
`protected abstract void`	`xFunc()` Called by SQLite as a custom function.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail
- FLAG_DETERMINISTIC
```
public static final int FLAG_DETERMINISTIC
```
  Flag to provide to create(Connection, String, Function, int) that marks this Function as deterministic, making is usable in Indexes on Expressions.
  
  See Also:
  
  Constant Field Values

Constructor Detail
- Function
```
public Function()
```

Method Detail

create

public static final void create(Connection conn,
                                String name,
                                Function f)
                         throws SQLException

Registers a given function with the connection.

Parameters:: conn - The connection.; name - The name of the function.; f - The function to register.
Throws:: SQLException

create

public static final void create(Connection conn,
                                String name,
                                Function f,
                                int flags)
                         throws SQLException

Registers a given function with the connection.

Parameters:: conn - The connection.; name - The name of the function.; f - The function to register.; flags - Extra flags to pass, such as FLAG_DETERMINISTIC
Throws:: SQLException

create

public static final void create(Connection conn,
                                String name,
                                Function f,
                                int nArgs,
                                int flags)
                         throws SQLException

Registers a given function with the connection.

Parameters:: conn - The connection.; name - The name of the function.; f - The function to register.; nArgs - The number of arguments that the function takes.; flags - Extra flags to pass, such as FLAG_DETERMINISTIC
Throws:: SQLException

destroy

public static final void destroy(Connection conn,
                                 String name,
                                 int nArgs)
                          throws SQLException

Removes a named function from the given connection.

Parameters:: conn - The connection to remove the function from.; name - The name of the function.; nArgs - The number of args for the function.
Throws:: SQLException

destroy

public static final void destroy(Connection conn,
                                 String name)
                          throws SQLException

Removes a named function from the given connection.

Parameters:: conn - The connection to remove the function from.; name - The name of the function.
Throws:: SQLException

xFunc
```
protected abstract void xFunc()
                       throws SQLException
```
Called by SQLite as a custom function. Should access arguments through value_*(int), return results with result(*) and throw errors with error(String).

Throws:

SQLException

args
```
protected final int args()
                  throws SQLException
```
Returns the number of arguments passed to the function. Can only be called from xFunc().

Throws:

SQLException